In an electrophotographic image forming apparatus, an electrostatic latent image formed on a surface of a photoreceptor is made visible by use of toner (developer) by a developing device. The toner used for making the electrostatic latent image visible is contained in a toner container, and sequentially supplied to the developing device from the toner container.
An image forming apparatus that operates at high speed consumes plenty of toner. Therefore, a toner container having a large volume is used in the image forming apparatus. Among these, a toner cartridge that supplies toner to a developing device by rotation of a toner container has been recently known. Most of such rotation-type toner containers are formed into a hollow cylindrical shape, and have a closed edge part and a discharge opening in the vicinity of the other edge part. The toner container is hereinafter referred to as a toner bottle.
A toner cartridge including a toner bottle is provided in an image forming apparatus such that a rotary shaft of the toner bottle becomes horizontal. Some toner bottles have spiral projections on their inner surfaces. The projections provided on each of the inner surfaces transfer toner toward a discharge opening by rotation of the toner bottle around the rotary shaft, so that the toner is discharged from the discharge opening.
The toner cartridge including the toner bottle further includes, near the discharge opening of the toner bottle, a toner supply section that (i) regulates an upper limit of toner quantity to be discharged from the toner bottle and (ii) discharges a certain amount of toner outside of the toner cartridge. In the toner cartridge including the toner supply section, a toner bottle discharge opening 30 is formed in an edge surface of a toner bottle 20, which edge surface is located in the vicinity of a periphery of the toner bottle 20, as shown in FIG. 9. Further, as shown in FIG. 8, a toner supply section 3 includes, above the vicinity of the toner bottle discharge opening 30, a toner discharge position regulatory partition 6 that regulates the toner quantity to be discharged from the toner bottle 20. The toner discharge position regulatory partition 6 causes toner to be discharged from a supply section discharge opening 5 of the toner supply section 3 in a case where the toner bottle discharge opening 30 reaches around a lower side of a toner cartridge 101. The toner discharge position regulatory partition 6 prevents toner discharged from the toner bottle 20 to the toner supply section 3 from flowing back from the toner supply section 3 to the toner bottle 20 in a case where the toner bottle discharge opening 30 reaches around an upper side of the toner cartridge 101.
The toner discharge position regulatory partition 6 allows toner itself contained in the toner bottle 20 to close the toner bottle discharge opening 30 from inside in a case where the toner bottle 20 contains plenty of toner. This prevents outside air from flowing into the toner bottle 20, thereby keeping an inner pressure of the toner bottle 20 so as not to be decreased. Therefore, toner is prevented from being discharged from the toner bottle 20. Consequently, a small amount of toner is discharged.